Generate Utf8Case.ser directly from UnicodeData.txt

Generate Utf8Case.ser directly from UnicodeData.txt

This allows getting rid of serialized/serialize.php. I also moved
includes/normal/Utf8CaseGenerate.php to maintenance/language/
generateUtf8Case.php and updated it to subclass Maintenance, as
it seems to be largely unrelated to normalization.

Using version 6.0.0 of UnicodeData.txt, the updated script generates
exactly the same serialized output as was previously checked in.

Also updated the Makefile to reflect the current set of .ser files
and added some .gitignore entries.

Change-Id: I05afece3dc4505a9f43993ac4d7726b37d9c6956